Drug interactions
Cyproheptadine + Fenfluramine
Severity: Moderate
Cyproheptadine and Fenfluramine: moderate interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Fenfluramine acts through release of serotonin and activity at serotonin receptors, and cyproheptadine is a potent 5-HT2 antagonist. Cyproheptadine may therefore blunt the anticonvulsant effect of fenfluramine, with possible loss of seizure control.
What this interaction means in plain words
Cyproheptadine and Fenfluramine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Cyproheptadine belongs to Respiratory; Fenfluramine belongs to Central Nervous System.
Why it happens
Pharmacodynamic antagonism at serotonin receptors, mainly 5-HT2, by cyproheptadine.
What to do
Avoid combining where possible, and monitor seizure frequency closely if cyproheptadine is needed. Reassess fenfluramine response if cyproheptadine is started.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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References
- Fintepla - FDA drug label (DailyMed) — openFDA / DailyMed
Other interactions of Cyproheptadine
- Cyproheptadine + Isocarboxazid Contraindicated
- Cyproheptadine + Phenelzine Contraindicated
- Cyproheptadine + Tranylcypromine Contraindicated
- Alfentanil + Cyproheptadine Major
- Belladonna and opium + Cyproheptadine Major
- Benzhydrocodone / acetaminophen + Cyproheptadine Major
Other interactions of Fenfluramine
- Fenfluramine + Isocarboxazid Contraindicated
- Fenfluramine + Linezolid Contraindicated
- Fenfluramine + Phenelzine Contraindicated
- Fenfluramine + Selegiline Contraindicated
- Fenfluramine + Tranylcypromine Contraindicated
- Almotriptan + Fenfluramine Major
Frequently asked questions
Can I take Cyproheptadine with Fenfluramine?
MediHelp rates the interaction as moderate. Cyproheptadine and Fenfluramine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Fenfluramine acts through release of serotonin and activity at serotonin receptors, and cyproheptadine is a potent 5-HT2 antagonist. Cyproheptadine may therefore blunt the anticonvulsant effect of fenfluramine, with possible loss of seizure control.
How serious is the interaction between Cyproheptadine and Fenfluramine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining where possible, and monitor seizure frequency closely if cyproheptadine is needed. Reassess fenfluramine response if cyproheptadine is started.
What other medicines interact with Cyproheptadine?
MediHelp also lists interactions of Cyproheptadine with, for example, Isocarboxazid, Phenelzine, Tranylcypromine. The full list is on the Cyproheptadine page.
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